<!DOCTYPE html>
<p>Spanner inside block with fixed height. There's unused space in the column where the spanner occurs.</p>
<p>There should be a blue square below.</p>
<div style="-webkit-columns:3; -webkit-column-gap:0; line-height:2em; width:12em;">
    <br>
    <br>
    <br>
    <br>
    <br>
    <div style="height:3em; background:blue;">
        <div style="-webkit-column-span:all; width:4em; margin-top:1em; height:1em; background:blue;"></div>
    </div>
    <br>
    <br>
    <br>
</div>
